The invention relates to a vertical boring and turning mill, comprising a tool ram, a rotationally drivable tool spindle arranged in the tool ram, and an auxiliary head which can be attached to the tool ram.
Known auxiliary heads of this type serve on vertical boring and turning mills to increase the rate of utilization. For example, plane surfaces are machined by means of a rotationally driven milling head, or they are used to produce bores, in particular threaded holes, in the workpiece arranged on the table, while the table is stationary. For these rotationally driven tools, a tool spindle which can be coupled to the tool in the auxiliary head is arranged in the tool ram.
For turning a workpiece rotating on the table, a corresponding turning tool is attached to the turning-tool ram. The feed of the turning tool in the horizontal and vertical directions is effected by corresponding movement of the tool ram. In this case, the workpiece is machined by a turning tool, as a result of which the machining time is determined. Also, deflecting forces arise in the direction of the axis of rotation during the machining of bores in the workpiece. These deflecting forces influence the machining accuracy, since the deformation of the tool ram that is caused by the deflecting forces becomes greater as the tool ram is moved further out of its slide. Although attempts are made to take these factors into account by appropriate dimensioning of the tool ram and its bearing arrangement, only a compromise is possible for this without a detrimental increase in the dimensions and the weight of a vertical boring and turning mill with predetermined dimensions of the table.